Clesar vogt



(No Model.)

0. VOGT.

MAGNETIC TELEPHONE.

No. 476,583. Patented June 7, 1892.

W/T/VESSES lNVE/VTUH ATTORNEY.

UNITED STATES PATENT OFFICE.

CZESAR VOGT, OF POSEN, GERMANY.

MAGNETIC TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 476,583, dated June '7, 1892.

Application filed September 14,1891. Serial No. 405,732- (No model.)

To all wh'om it may c0ncern:

Be it known that I, CAESAR VOGT, electrician, of the city of Posen, Kingdom of Prussia, in the German Empire, have invented a new and useful Improvement in Magnetic Telephones, of which the following is a specification.

This invention relates to a magnetic telephone having both opposite poles turned against the vibrating membrane; and the object of this invention is a device by means of which the poles can be displaced against each other, so as to be more or less distanced from the vibrating membrane. One pole is placed right opposite the center of the vibrating membrane and the other pole, being annular shaped, concentrically surrounds the first.

In the accompanying drawing, forming part of this specification, the figure represents a longitudinal section through the telephone, showing the relative positions of the poles to each other, both poles equidistant from the vibrating membrane.

M is a horseshoe steel magnet, to one branch Z) of which the center pole up is fastened by means of a screw. lhe other branch (L of the magnet carries at its free end the annular pole s p, concentrically surrounding the inner pole, which forms the core for the bobbin 6.

0 ff are protecting-plates for the same.

j may be turned without leaving its seat.

The front end of the screw-shaft, being reduced in diameter, is threaded and fits into a tapped hole of the branch at of the magnet.

It will be easily understood that by turning the screwj to the right the annular pole will be distanced from the vibrating membrane on and by turning it to the left the said pole must approach the vibrating membrane, as in Fig. 2. This device of adjusting the poles to the vibrating membrane otters the advantage that the instrument is made sensitive in the highest degree, and the shape of the outer pole surrounding the inner pole and the bobbin has besides the advantage that the bobbin between its protecting-platesffand in the annular pole is everywhere well protected against any outside damage.

\Vhat I claim as my invention, and desire to secure by Letters Patent, is

In a double-poled telephone, a device for adjusting the outer annular pole with relation to the membrane, composed of a horseshoe steel magnet carrying at the end of one of its branches the bobbin with an iron core as the inner pole and on the other branch an iron cylinder surrounding said bobbin as the other pole and of a screw having a head countersunk into and secured by a washer upon the branch carrying the bobbin and havinga screw-threaded shaft engaging in a tapped hole in the other branch of the steel magnet, substantially as set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

O/ESAR VOGT.

IVitnesses:

W. P. KENEALY, FRANK FRIEDRICH. 

